The original 2010 study was seen as a revolution in our understanding of life. "If true, such a finding would have important implications for our understanding of life's basic requirements since all known forms of life on Earth use six elements: oxygen, carbon, hydrogen, nitrogen, phosphorus and sulfur," said a statement released Monday from the journal Science.

The thought of an organism that used arsenic instead of phosphorus in its DNA would suggest that life could emerge under radically different circumstances than the science community assumed. It would also suggest that life on other planets could be more varied than expected.

However, the two more recent studies refute the original "arsenic life" report. The 2010 study, headed by Felisa Wolfe-Simon and a team of researchers, acknowledged in their original study that there were low levels of phosphorus in their study samples. Wolfe-Simon and her team argued that the amounts of phosphorus were too low to influence the GFAJ-1 bacterium.

Two recent studies disagree. "The basics, growing the bacteria and purifying the DNA, had a lot of contamination problems," wrote microbiologist Rosie Redfield of the University of British Columbia in February. Redfield is the author of one of the newly published papers.